Top and bottom surface unit of a mattress



FIG. 1 is a top, rear and left side perspective view of a top and bottomsurface unit for a mattress according to the new design, the brokenlines showing the side are for illustrative purposes only and form nopart of the claimed design;

FIG. 2 is a top plan view of the top and bottom surface unit of amattress shown in FIG. 1; the opposite bottom plan view being a mirrorimage thereof;

FIG. 3 is a left side elevational view of the top and bottom surfaceunit of a mattress shown in FIG. 1; the opposite right elevational viewbeing a mirror image thereof. The broken lines showing the side are forillustrative purposes only and form no part of the claimed design; and,

FIG. 4 is a front elevational side view of the top and bottom surfaceunit of a mattress shown in FIG. 1; the opposite rear elevational viewbeing a mirror image thereof. The broken lines showing the front are forillustrative purposes only and form no part of the claimed design.

The ornamental design for a top and bottom surface unit of a mattress,as shown and described.